UVB 309nm in Various Fluorescence

[dabateman]

Hi Dave.

Yes I have Mercury UVC, but I have been making some UVC LEDs to try out too.

I have 265nm & 275nm UVC LEDs sets as well now.

 

Wow that changes things. Yes some ZWB3 over top those LEDs would allow you to do UVC induced UVB or UVA or visible.

But be super careful with that 275nm light. That is right near the most toxic wavelength for us Humans. Cover up well when working with it.

[colinbm]

Thanks Dave, I didn't know that 275nm was any worse then 254nm ?

[dabateman]

Yes 265nm and 275nm are worse than 254nm.

You can see that from Ulf's dangerous plot from ISO standards.

They are closer to the absorption and disruption wavelengths of DNA and amino acids, that make up proteins in your body.

 

Thus why many water sterilizer use 270nm.

 

This paper can give you some context

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4702654/

[colinbm]

Well why does Andy criticise me when I stress 'Cover Up' with 'Full Face Mask', when these young adults on here talk about playing with UV A B & C & no one comes to my rescue ?

I do get pee'd off !

Andrea has started discussion on this before, but it never seems to get completed, We need a standard reply with the best standards !

[dabateman]

Colin,

I honestly think Andy was in general agreement with you to wear safety equipment. The problem is what safety equipment.

Cadmium first found that the orange Uvex glasses aren't the best for UVA protection, as they leak at 380nm. Mine leak there too, much more than my Amber Uvex glasses. However, my Orange Uvex glasses protect much better against UVC than my Amber glasses.

So I am glad I have both.

So if the industry whom makes this stuff, could get their act in order, than recommendations would be easier.

[Andy Perrin]

The face shield we were discussing was for UVC and would have provided an unknowable degree of protection against other wavelengths. Fandyus was after UVB protection. I still think covering up and using sunblock (with some checks for coverage) is a better strategy. UVA is a different story— eye protection is the main thing in UVA, and as discussed the optimal glasses for UVC are different than for UVA.

 

Colin, it wasn’t meant as a personal attack.

[Fandyus]

What do you mean by sunblock? A sunscreen? I was actually considering getting a polycarbonate face shield for future uses - alongside with a pair of deep orange goggles from a work needs store, that are rated to protect even against blue light.

[Andy Perrin]

Sunblock and sunscreen are both different lotions you apply to your face to protect from the sun, but sunblock uses a physical mechanism (they have metal oxides with a bandgap that starts in UVA) and sunscreen uses a chemical mechanism (they are essentially organic dyes with electronic transitions in UV). Polycarbonate face shields of the brand I linked before work for UVC, although they block an UNKNOWN amount of UVA and UVB, and aren't rated for those bands. I keep trying to explain it, but I feel like nobody understands the distinction between something that's been tested by the EU or FDA and something that hasn't been. Sunblock has been tested by the FDA in the US at least. I would trust something with zinc oxide or titanium dioxide with a high SPF. You just have to make sure you don't miss any spots (but hey, you have a UV camera so that's not hard...).

[Fandyus]

Hmm I see, I get your frustrations. I only want to get one for extra protection. My father has spares so I can get one for free probably.

[colinbm]

Uvex Ultraspec Orange Safety Glasses - Eyewear for UV Protection

The Uvex Ultraspec 2000 glasses help in absorbing more than 99.9% of harmful UV light.

https://www.cureuv.com/products/orange-safety-glasses-for-uv-protection-uvex-ultraspec

 

UV Face Shield with Clear Polycarbonate Protection

99.99% protection against all UVA, UVB and UVC wavelengths

https://www.cureuv.com/products/uv-face-shield-with-clear-polycarbonate-protection

 

Your eyes & face need protection

Heavy cotton clothing will protect the rest of your body.

[Andy Perrin]

It's interesting that it's only OD3 and OD4 protection for those, respectively. Whether that's enough will depend on how strong the source is. My laser goggles are OD7, but for typical LEDs I'm sure OD3 is fine for indirect light. On the other hand for a 100W LED source (Fandyus was discussing this with me elsewhere), you would want more protection. If you used both goggles and polycarb face shield simultaneously it would be like OD7 though.

[Fandyus]

Yes, I will attempt to mount a 100w 395nm LED array. It was very cheap so I'm not sure it's actually 100w. Before I work with it I will get some deep orange goggles. I'll be able to test how well they work with my own sight since 395nm is visible to humans.

[Andy Perrin]

Fandyus, 395nm is visible to humans only barely. People routinely fry their eyes with 405nm lasers because they don’t account for the fact that even though they can barely see the laser dot, it’s actually very high intensity and can wreck your retina. A “sight check” is NOT a way to check safety equipment. I can tell I’m not getting through on the need to rely on proper testing bodies but I can’t stop people who are determined to do something dumb. I’m tired of discussing this and I think this is the last I want to say about it.

[Fandyus]

Putting on the goggles and seeing if there's any violet should be enough. Plus the goggles will be orange and rated for blue light protection. If only an invisible amount is leaking, it should be okay, but then again, it will be a deep orange pair of glasses, you advised me in the last time to get those for when I want to look on fluorescent blacklights directly. Like I don't have a spectrometer, how else am I supposed to test the goggles?

It's not a laser and I want be pointing it in my eyes either so I think you can be calm.